--AND2 MODELUSE WORK.ALL;entity AND2 is    generic(constant TPLH:TIME:=4 ns;            constant TPHL:TIME:=6 ns);	    port ( I1,I2:in BIT; O: out BIT);end AND2;architecture BEH of AND2 ISbeginP1: process(I1)variable O_TEM:BIT:='0';variable O_TEM_M:BIT; 	BEGIN	O_TEM_M := I1 AND I2 ;	if ( O_TEM='0' AND O_TEM_M='1') then	   O <= I1 AND I2 after TPLH;	   elsif (O_TEM='1' AND O_TEM_M='0') then	        O <= I1 AND I2 after TPHL; 	        else O <= I1 AND I2 ;	 end if;	  O_TEM:= I1 AND I2 ;end process P1;end BEH;